Pump



ET AL 3,411,452

Nov. 19, 1968 J. J. CZARNECKI PUMP 3 Sheets-Sheet 1 Filed Oct. 7, 1966INVENTORS JERZY J. CZARNECKI 8 PETER ARKWRIGHT 7/ A iiw ATTORNEYS Nbv.19, 1968 J, czARNEcK ET AL 3,411,452

PUMP

3 Sheets-Sheet 2 Filed Oct. '7, 1966 INVENTORS :JERZY J. CZARNECKI 8PETER ARKWRIGHT ATTORNEYS ET AL PUMP 5 Sheets-Sheet 5 .1. J. CZARNECKIRELIEF VALVE SERVO Nov. 19, 1968 Filed em.

COOLER INVENTORS JERZY J. CZARNECKI 8 PETER ARKWRIGHT ATTORNEYS RELIEFVALVE FiLTER BY QM,

REDUCTION {I64 PILOT VALVE F l G. 2

United States Patent 3,411,452 PUMP Jerzy J. Czarnecki, Princeton, andPeter Arkwright, Pennington, N .J assignors to De Laval Turbine Inc.,Trenton, N..I., a corporation of Delaware Filed Oct. 7, 1966, Ser. No.585,133 7 Claims. (Cl. 103152) ABSTRACT OF THE DISCLOSURE A pulsatorpumping system comprising a pair of mechanic-ally connected pulsators isprovided with a positive, reversible pump in its driving liquid system,which delivers driving liquid alternately to the pulsators. Make-upliquid is delivered by a second pump to the driving liquid system, and acombination of check valves and a relief valve permits flow of liquidfrom one side of the reversible pump to the other when the pressuredifferential becomes too high. Interconnections are provided forprepressurization of a collapsed pulsator by liquid delivered from theexpanded pulsator.

This invention relates to pumps and has particular reference to pumps ofthe pulsator type such as those of Patents 2,836,121, 3,048,114,3,080,821, 3,194,169, and 3,212,447.

Heretofore in pumps of this type it has been usual to provide thedriving liquid from a reservoir to a phasing valve for distribution totwo or more pulsators so operated that their joint delivery of pumpedliquid was at a substantially continuous rate with minimum pulsations.During return strokes of the individual pulsators the driving liquid wasreturned to the reservoir. Since the supply to the pulsators has usuallybeen at very high pressures, this circuit of the driving liquid involvedconsiderable losses.

One of the objects of the present invention is to provide a system inwhich at least one pair of pulsators operates with direct flow from thecollapsing one to the expanding one through a pump capable of producinghigh pressure, with only minor flow, essentially of make up nature,involving a reservoir. By this arrangement efficiency is substantiallyincreased.

Other objects of the invention relate to the attainment of operationsleading to satisfactory control and pumping, and these will become moreapparent from the following description, read in conjunction with theaccompanying drawings in which:

FIGURES 1A and 1B are sectional views showing a preferred type of pumpprovided in accordance with the invention; and

FIGURE 2 is a diagram showing particularly the driving and control meansinvolved.

Referring first to FIGURES 1A and 1B, the latter being a continuation ofthe righthand portion of the former, with repetition of the elementsconstituting the central portion of the pump, there is provided ahousing 2 having its respective ends closed by cap members 4 and 6providing chambers for the pumped liquid which have respectiveconnections 8, 9, 10 and 11 running to inlet and outlet check valveassemblies through which pumped liquid is drawn from a supply anddischarged to a point of use. The inlet and outlet check valveassemblies are conventional and not illustrated, being of types shown inthe patents previously referred to. The present pump is particularlydesigned to operate at high pressures and with large deliveries, thoughthe aspects of the invention are equally applicable to pumps of smallsize and/or involving relatively low delivery pressures.

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Two pulsators are involved located at opposite ends of a rod 12 whichpasses through packing 14 in a central member which separates tworegions receiving the driving liquid. As will be apparent from FIGURES1A and 1B, the pump is symmetrical about this central member. The rod 12connects the pulsator assemblies which are respectively designated 16and 18. Since these are identical in form, a single description willsuffice with the same numerals applied to both assemblies. Referring toeither assembly, a rigid plate member 20 has secured to it a firstpulsator section 22 which is connected by a rigid coupling ring 24 to asecond pulsator section 26 which is anchored to a fixed member 28secured in the housing. The use of two sections is to provide anextended working stroke, and each section is. of the type illustrated inBrowne Patent 3,194,169, comprising a flexible, expansible member of arubber-like material formed with annular folds within which are locatedrigid rings to maintain proper shape and control the desired expansionand contraction. In this type of pump oil is desirably used as thedriving liquid, and the pulsator composition is chosen to be unatfectiveby the oil used, and also to be unalfective by the pumped liquid.Various synthetic rubbers are suitable for this purpose.

The respective left and righthand pumping chambers provided within thepulsators are designated 30 and 32. With these chambers therecommunicate the respective passages 36 and 38 for inflow and outflow ofthe driving liquid, these having connections as described hereafter.

Valve assemblies 40 and 42 are provided in association with therespective pulsators to cooperate with seats 44 and 46 formed at theends of the members 28 which are annular in form. The valve assembliesare the same and only one need be described. Each comprises a valvemember 48 having a body of rigid material and an extension 50 formed ofa rubber which by conformity with a corresponding seat will provide atight seal. Rings 52 located in grooves in the rod limit inwardmovements of the valve members 48 under the action of springs 54 backedup by rings 56 also in grooves in the rod. The valve members, during rodstrokes, are accordingly removed from their seats by the rings 52, butseat under the forces of the springs 54 which are compressed by therings 56.

Spiders 58 and 60 provide guidance for the rod 12 and hold in positionliners 62 and 64 the cylindrical inner surfaces of which serve to mountthe slide valves 66 and 68, the inner ends of which are of spider formengaged by springs 70 and 72 backed up by the spiders 58 and 60, thesprings normally urging the valves 66 and 68 against stops provided bysnap rings 78 and 80 located in grooves in the liner. The valve 66 isprovided with an annular groove 82 having communication with itsinterior and arranged to provide communication through small holes 84which are in communication with piping 86 (FIGURE 1A) which runs to acheck valve 88 (FIGURE 1B) communicating through an opening 90 with theface of the valve seat 46 at a point beyond the region engaged by p thevalve 48, the check valve 88 opening so as to permit flow from left toright. In identical fashion the valve 68 is provided with an annulargroove 92 communicating with its interior and cooperating with smallholes 94 through the liner 68 communicating with piping 96 connectedthrough check valve 98 with an opening 100 in the seat 44 beyond theregion engaged by the lefthand valve 48. Flow through the piping 96 isfrom right to left.

Openings 102 in the liner 62 communicate with a groove 106 which has anexternal connection to an oil supply reservoir, not illustrated inFIGURE 1A. Similarly, openings 104 in liner 64 communicate with anannular groove 108 also having an external connection to the reservoir.The openings 102 and 104 cooperate with the 3 respective valves 66 and68 under some conditions as hereafter described.

The liners 62 and 64 are provided with large openings and 112,respectively, providing free communication between the interiors of theliners and the driving oil passages 36 and 38.

Referring to FIGURE 2, this diagrams the pump driving and controlapparatus, and indicates some of the elements previously described suchas the cross-connections 86 and 96, the check valves 88 and 98, thepassages 90 and 100, and the various passages 106, 108, 36 and 38.

The driving liquid, oil under suitably high pressure is provided throughthe connections 114 and 116, and also relieved through theseconnections, by a reversible pump 118 driven by a motor 120 which willnormally operate at constant speed.

The pump 118 is preferably a positive pump of the multiple piston typewhich may have its flow reversed by the tilting of a cam plate 122 whichacts upon rotating pistons in individual cylinders having connection tovalve passages in a valve plate adjacent to which the cylinders rotate.The passages are connected to the valve ports which serve for inflow andoutflow reversibly depending upon the position of the cam plate 122.Pumps of this type are well known, the Lucas pump design being typical.When delivery is to be reversible or variable, provisions are made fortilting the cam plate 122, and in the present instance this is effectedby connection of the cam plate to a piston 124 of a servo 126, the endsof the cylinder in which the piston moves being connected to lines 128and 130 for the entrance and exit of piston-positioning oil. When apiston is at one limit of its movement the pump 118 will receive oilthrough connection 116 and deliver it through connection 114, and whenthe piston is at the other limit of its movement the pump will receiveoil through connection 114 and deliver it through connection 116.

The respective lines 114 and 116 are connected through check valves toprovide flow therefrom through an adjustable high pressure relief valve136 if pressures become excessive. The downstream connection of therelief valve is to check valves 138 and 140 which may respectivelydeliver oil to the connections 114 and 116.

A constant delivery pump 142, such as a multiple screw pump is driven bya motor 144 which desirably operates at constant speed, the pumpreceiving oil from a reservoir 146 and delivering it through a filter148. The outflow from the filter may pass through two connections. Oneof these is indicated at 150 and delivers oil through an adjustablereduction valve 152 to the line 154 which connects to the inputs of bothcheck valves 138 and 140. This line provides makeup. Connection 150 alsoruns to an adjustable relief valve 156 which permits oil passage whenthe pressure exceeds a predetermined value. Oil flowing from the reliefvalve passes through a cooler 158 and back to the reservoir throughconnection 160. The second connection 162 from the filter 148 suppliesoil to a pilot valve 164 from which outfiowing oil resulting frompressure relief passes through line 166 back to the reservoir 146. Thepilot valve 164 has output connections at 167 and 169 through adjustableorifices, which may be in the form of adjustable valves 168 and 170,there orifices communicating with the servo lines 128 and 130.

The pilot valve 164 is of a conventional supply and relief type. Itsusual moveable element is operated by a mechanical connection 172through reduction gearing 174 by the motor 144. Its cycle is such as toproduce reversal of the pump 118, by motion of piston 124, at a suitablecycling rate for operation as will now be described.

Assume at a start of operation that the lefthand pulsator (FIGURE 1A) isfully collapsed and the righthand pulsator (FIGURE 1B) is fullyexpanded. At this time the valve 40 closes the chamber 30 within thelefthand pulsator, limiting its further collapse by trapping the oil 4therein and concurrently limiting further righthand movement of the rod12.

The lefthand slide valve 66 closes off both ports 84 and 102, theclosing off of the latter preventing communication between the regionwithin the slide valve and the return line to the reservoir. On therighthand side of the pump. the pulsator is now fully expanded and thechamber 32 is at maximum volume.

Valve 42 is held open and well spaced from its seat 46 by the action ofring 52.

The righthand slide valve 68 opens the port 94 to the pressure withinthe chamber 32, and the port 104 is open to the line 108 running to thereservoir.

The beginning of the next stroke, which involves the lefthand movementof the rod 12, is initiated by the movement of the pilot valve 164 underthe action of motor 144 through the reduction gearing 174 to effectpositioning of the cam plate 122 of the pump 118 to cause that pump topump oil from passage 38 (FIGURE 1B) through connection 116 and deliverthis oil through connection 114 to the passage 36. The oil pressureforces the valve 40 from its seat so that oil enters the lefthandpulsator causing it to expand and force the product liquid outwardlyfrom the left product chamber. Shortly after the rod 12 starts to move,the valve 40 is carried with it by the ring 52 opening a wide passagefor oil flow into the chamber 30.

Simultaneously, the righthand pulsator is contracted by the pull of rod12 and the product liquid accordingly enters the righthand productchamber from its supply.

The respective expanding and contracting actions of the pulsatorcontinue, and during the major part of the stroke the righthand slidevalve 66 remains in its initial position closing the ports 84 and 102.

The slide valve 68 moves at the very beginning of the stroke to closeoff the port 104 and thus cut off the communication between the chamber32 and the oil reservoir, the slide valve 68 moving with ring 76 on therod 12 under the action of the spring 72. Its movement terminates withits engagement with the fixed snap ring 80.

The conditions so achieved continue until near the end of the lefthandstroke of the rod 12. As the end of this stroke is approached, the port84 is opened by engagement of the ring 74 'with the slide valve 66. Justbefore this occurs, but substantially simultaneously, the valve 42 willreach its seat, and while a definite volume of liquid will then betrapped in the chamber 32 some further move-ment of the rod 12 may occurdue to the expansibility of the righthand bellows. But when the port 84is opened, a small amount of high pressure driving oil may pass throughthe connection 86, check valve 88 and passage 90 to relieve excesspressure in the lefthand chamber 30 and raise the pressure in thechamber 32 in preparation for the next stroke. Slight further movementof the rod 12 causes the slide valve 66 to uncover the port 102permitting flow to the reservoir with drop of pressure. But when thisoccurs the pressure within the chamber 32 which has been raised ismaintained by the closure of check valve 88. In view of thecommunication with the reservoir any further driving oil through thepassage 36 is diverted to the reservoir with cessation of expansion ofthe chamber 30.

The parts are now in their initial position first described except thatthe conditions are reversed between the righthand and lefthand elements.The plate 122 'will now be shifted by the pilot valve action on piston124 to effect operations to move the rod 12 to the right withcorresponding events. Since these events are the same except for thereversal of movement and elements, they need not be separatelydescribed.

Reference may now be made to various control actions, giving particularconsideration to FIGURE 2.

The function of the cross-connections 86 and 96, including therespective check valves 88 and 98 is to depressurize the chamberapproaching the end of its expansion stroke with utilization of thepressure to prepressurize the chamber which is about to begin itsworking stroke. When the prepressurizing occurs the pulsator chamber inwhich the pressure is caused to rise is closed by its valve 40 or 42. Inexplanation of the utility of the pressure transfer operation it may bepointed out that under the high pressures which are involved even rigidwalls will yield to a considerable extent so that the geometry ofchambers involved cannot be considered by any means fixed. When pressureis relaxed the volumes of the chambers which have been under high'pressure will decrease; and upon repressurizing the volumes willincrease. In pumps of the general type herein being considered suddenrelief of pressures will produce shocks essentially of a sound typewhich may be extremely violent giving rise to highly objectionable noiseand vibration, resembling to a considerable extent the shocks producedby the ordinary phenomenon of water hammer. By permitting depressurizingthrough the cross-connections before relief of pressure by openingcommunication to the reservoir, the shock aspects are greatly reduced,and for this purpose it is desirable that the liquid transfer involvedshould be attenuated as by the small passages involved at 82 and 84 andrestriction to free flow afforded through the pipe connections and thecheck valves. Under these conditions the pressure equalization takesplace smoothly. At the same time, by reason of the pressure, the chamberwhich is about to receive driving liquid will be preliminarily expandedto take up the slack so that the oil driving pump 118 is relieved ofthis function. Reverse flows through the cross-connections are preventedby the check valves. At the end of a stroke the opening of the workingchamber to the reservoir involves some loss of the driving oil from thetheoretically closed system which involves the back and forth flowthrough the pump 118. The pump 142 is designed to provide make up andalso take care of other aspects of operation involving loss of oil fromthe desirably closed system just mentioned. The pump 142 (which alsosupplies the small amount of oil necessary to operate the pilot valve164) provides a desired pressure in the connection 154 through thereduction valve 152 with which there is associated the relief valve 156which takes care of excess delivery, the pump 142 being desirably of apositive type (e.g., a screw pump) driven by a constant speed motor 144to provide a volume flow of oil which is in excess of normalrequirements. The check valves 138 and 140 provide flow from the line154 to the respective connections 36 and 38 whenever these connectionshave pressures substantially less than the pressure in the line 154.This arrangement takes care of pressure deviations which may occur bothin normal operation and due to deviations from normal operations whichmay well occur though in most cases they will not represent suchabnormal operations as could be considered maloperations. Suchdeviations from normal operation may be due to such matters as temporaryobstructions or overloads in the product connections of the pump- Thecheck valves 132 and 134 in combination with the settable relief valve136 and the check valves 140 and 138 serve also to take care of abnormalconditions. For example, if the pressure in the line 36 rises abnormallyabove the setting of the relief valve 136 there can be a flow throughcheck valve 132, relief valve 136 and check valve 140 to bypass flowtothe line 38 which at such time will ordinarily be at the normalpressure of the system, considering motors 120 and 144 operating atsubstantially constant speeds, and therefore at speeds bearing asubstantially constant ratio to each other. Normal adjustments should besuch that the operation of the pump 118 should be reversed shortly aftersuch delivery to the working chamber as would displace it to the end ofits working stroke. If an ideal operation could be achieved in which thereversal of the operation of pump 118 could be timed precisely with theachievement of full expansion of the bellows, the working oil would beessentially of fixed volume transferred between the bellows. Obviously,this situation is unattainable due to the desirability of obtaining fullstrokes despite variations in the product delivery which in turn wouldimpose variable loads on the pump 118 variably loading its motor toproduce slight deviations in speed, expansibilities of oil spacesinvolved due to extremely high pressures as mentioned above, theinherent variations of volumes due to the bellows operating underdifferent pressure conditions, etc. The make up and other provisions forflows described particularly in connection with FIGURE 2 take care ofproper operation despite these disturbing factors.

While there has been illustrated a single pump unit having a pair ofinterconnected pulsators, and such a single unit may suflice in manyinstances for the desired pumping action, it may be noted that the unitsof a com plete pump may be multiplied as much as desired: for example,three units with three sets of paired pulsators. In such a case, it isdesirable that the units should operate with displaced phases, andconsidering a cycle as involving a complete reciprocation of a rod 12 ofa unit the phased displacements may be 60, i.e., the units would achieveends of product pumping cycles at 60 intervals, there be ing for eachunit two product pumping cycles in each complete cycle. This phasing canbe achieved in an obvious fashion by having the drive 172 from thereduction gearing 174 for the respective pilot valves, one for eachunit, so arranged as to operate the pilot valves with the correspondingphase differences. The result, of course, is to achieve more uniformflow.

It will be evident that achieved in accordance with the invention is thedirect low-loss transfer of Working oil between the paired bellows of aunit, without involving a circuit including a reservoir such as 146which may be small and of a volumetric capacity only sufiicient to takecare of the make-up requirements as described.

It will be evident that various changes in details may be adoptedwithout departure from the invention as defined in the following claims.

What is claimed is:

1. Pumping means including a pair of pump units, each of which comprisesa flexible pulsator and an associated housing defining a driving liquidchamber and a driven liquid chamber separated by said pulsator andvalved inlet and outlet connections to said driven liquid chamber; apositive pump of reversible flow type having connections to said drivingliquid chambers so that said positive pump delivers driving liquiddirectly from one driving liquid chamber to the other, and vice versa;means for driving said positive pump to elfect flow reversal thereby,wherein the improvement comprises an auxiliary pump delivering make-upliquid under pressure, means delivering said make-up liquid to thedriving liquid system between said positive pump and one of said drivingliquid chambers, means delivering said make-up liquid to the drivingliquid system between said positive pump and the other of said chambers,and valve means normally preventing flow of driving liquid between saidsystems except through said positive pump, but permitting flow betweensaid systems if the difference in pressure between said systems exceedsa predetermined value.

2. Pumping means according to claim 1 in which the pulsators aremechanically connected so that as one driving liquid chamber is expandedthe other is contracted and vice versa.

3. Pumping means according to claim 1 comprising means effecting closureof each driving liquid chamber at the condition of a minimum volumethereof to trap driving liquid therein.

4. Pumping means according to claim 2 comprising means effecting closureof each driving liquid chamber at the condition of a minimum volumethereof to trap driving liquid therein.

5. Pumping means including a pair of pump units, each of which comprisesa flexible pulsator and an associated housing defining a driving liquidchamber and a driven liquid chamber separated by said pulsator andvalved inlet and outlet connections to said driven liquid chamber, apump supplying driving liquid under pressure, means delivering saiddriving liquid supplied by said pump alternately into the driving liquidchamber of one of said units and into the driving liquid chamber at theother of said units, means mechanically connecting said pulsators sothat as one driving liquid chamber is expanded, the other is contracted,and means efiecting closure of each driving liquid chamber at thecondition of minimum volume thereof to trap driving liquid therein,wherein the improvement comprises means effecting transfer of drivingliquid under pressure from each driving liquid chamber at the end of itsexpansion to the other driving liquid chamber when the latter is closedthereby to relieve the pressure in the former and prepressurize thelatter preparatory to its expansion.

6. Pumping means according to claim 5 in which each of saidtransfer-elfecting means includes a check valve to permit fiow onlytoward the collapsed chamber.

7. Pumping means according to claim 5 in which said pump and said meansdelivering said driving liquid supplied by said pump comprises apositive pump of the reversible flow type having connections to saiddriving liquid chambers so that said positive pump delivers drivingliquid directly from one driving liquid chamber to the other.

References Cited UNITED STATES PATENTS 731,241 6/1903 Steiner 103462,625,886 1/1953 Browne 103-150 2,753,805 7/1956 Boivinet. 2,768,500 10/1956 Tyler. 3,164,101 1/ 1965 Van Nederynen 103152 3,192,860 7/1965Hardison.

ROBERT M. WALKER, Primary Examiner.

